WR 4th gear wheelies easy !!!!!!

WR 426 ,YZ timed,48pj{little rich}stock needle in stock clip,175 mj,our own {Western Fabrication Specialties}exh insert,stock gearing,AIR BOX LID ON !!!! We ride at 4000 ft.This baby rips and it is respectfully quiet.I want to thank all of you who are responsible for this sight and for all who have volunteered thier time and research .


Tell us more about this exhaust insert. I've been thinking about fabing up my own but I don't work in a shop anymore and favors are hard to ask for. I don't want to use the stock insert, too much power loss and nobody seems to make an aftermarket exhaust that wont rip your ears off and get me thrown off good land. One of the members here said he made an insert with a 3/4" through hole and claimed it worked well.


We build a nice insert that is simular to the Baja D.My friend has a 2000 wr 400 and he purchased the Baja D insert last year.We thought we could improve the flow a little without noise increase.We rode side by side yesterday and swopped bikes and both agreed the sound was about the same.As far as exh. flow we have more outlet area .My bike which is a 426 wr is quite a bit quicker than my freinds 400.I think that has alot to do with the size,titanium Vs,etc.We're thinking about selling these inserts for around the $50 but we need some people to try these out for themselves and post back their thoughts.We think we have a real good product so if your interested in trying one I'll sell you one for $20 to cover materials and shipping .

i just got a 01WR426 and would be interested in testing your insert. Let me know

rbarcellona@autotester.com (software company/not car testing)


I have a '99 WR400 with the stock silencer & Thumper Racing insert. I'd be interested in doing a comparison - can you send me a pic?

Have you done any testing with a sound meter?



Trust me I was never implying that I was looking for any free product only information about where this insert could be obtained and the cost and other non top secret specs. Dana I would be happy to pay $20.00 to test your insert and give you feedback. Please post how to get one. Mojo, I don't understand your shot at me and Brian. Maybe you don't understand that the information we share here is FREE. That is the whole idea and that is why this site was started, to share information. Don't believe me ask Bryan. Furthermore I don't need anyone to tell me how to make one. Besides being a Mechanical Engineer I worked on the bench in machining and fabricating. Maybe if you would stop trying to insult us I could offer Dana some help FREE of charge. I use 3d solids mechanical CAD every day and could model a design for him FREE. This site is about friendly collaboration and no one is trying to horn in on Dana's business. So chill. :)



'00 WR 400





I'm interested! I'll e-mail you Dana. I use a WB R4 on my 01 426, but am worried about the noise. I could try your insert out and give you a comparison of one of the better (and loudest) aftermarket mufflers.

Hey Dana - no e-mail posted on your profile. If you are interested in selling me one of your inserts - you'll have to e-mail me! (please do!)

[This message has been edited by Michael (edited 04-30-2001).]


Geez, who's in a worse mood today, you or me. Was I taking a shot at you and brian? I was just pointing out the obvious fact that you asked a question about the insert and he replied about what it would do; even referring to it as a great "product".

Mcarp posted straight away what he had done with a sink drain screen. That's free information. Cheap too.

If I embarrassed you, golly, sorry about that (that was a "shot"). I'm fully aware of the great information one can derive and contribute to this most hallowed of websites. Don't lecture me. This guy's selling a product. You chill too.

I'm not offended - just misunderstood :)

I wasn't asking for a free part - for $20 it's really hard to go wrong. I was just looking for a little more info BEFORE coughing up $20 & putting something on my baby.

Like Russ (& Dana), I'm a mechanical engineer. I have a little bit of experience with exhaust systems for small gas turbines. I was thinking I might be able to provide some true comparative sound data as I have the stock muffler with the Thumper core & the stock core. Yes, if I really got motivated I could design & build my own insert but I don't have the time and I'm just not that motivated.

Dana - contact me via email if you'd like. I'm interested in your insert & helping you out.


[This message has been edited by Brian Meadows (edited 04-30-2001).]

Brian and RussP,

I think your missing the point with Dana here. See he has something he wants to SELL for a presumable PROFIT. He isn't going to send you info on HOW he did it because then you would do it without giving him money.

Sometimes information isn't free, right Dana?


I didn't mean to start a fight.Seems as though I've been stirring the pot all over in this sight.We are Westen Fabrication Specialties in MT.We build custom snowmobiles and cicle track chassis.We've had a ton of tuning experience{50 years combined}.No we haven't put a sound meter around this insert.But as a comparison it is close to the Baja Des.We do no that it flows more.A motor needs a certain amount of exh. back pressure to retain bottom end power.If the motor is designed for peak power at the upper RPMs with open exhaust and the exh is resticted through baffles,mufflers,etc.,then its been killed from top to bottom.The same goes for a motor that produces torque right off the bottom with a some what restricted exh.and you open up the exh.wide open it fades the bottom grunt and there never was a top through design limitations.The stock WR YZ motor is one of the most amazing creatures on earth.I don't know how many of you youngsters that own one of these studs realise what you've got.My hat is off to Yamaha!!!!!!!!We put this insert in with WR timing and changed to a 170mj{4000ft and 60 degrees }It had almost uncontrollable bottom and mid but just built revs ontop.Then we went to the Yz timing and in my opinion made a new bike.Now it still has the grunt to pull any technical without an uncontrolable burst and that magical mid hit that makes the front wheel useless with a respectfull top end .I told Russ P that I would sell him an insert for $20 just to try.I'll sell a few more but in diiferent parts of the country.I shouldn't be doing this because I got this gut feeling my email will flood but here go's. fastboys@mcn.net Russ contact me for info.Remember to look to see what my set-up is as far as jetting,altitude,etc.Yours may differ so adjust according.I need your imput on set-up also. Dana Young

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